And elmer g



- p the production of di-substituted guanidines,

and :moreparticularly diarylguanidines, such as diphenylguanidine, ditolyguanidine,

Reissued Apr. 7, 1925.

UNITED-STATES,

. I -w p JOHN YOUNG, OE CALDWELL, JERSEY, AND' CROAKMAN, OF BUFFALO,- v 7 EW YORK, ASSIGNOBS TO N'ATIONAL ANILINE & CHEMICAL COMPANY, INC.,

Re.',v 16,040

PATENT OFFICE.

OF NEW IYOBK, N. Y., A CORPORATION OF NEW- YORK.

PRODUCTION OF DIARYLGUANIDINES.

. i I I P v No Drawing. Original "no 1,446,818, dated February 2.7, 1923, Serial No. 574,297, filed July 11, 1922. I Application tor reissue" filed February 3, 192 5. Serial-No. 6,666.

' To all tuhom it may concern:

Be it known that we, JOHN YOUNG, asubject of the King of Great Britain, residing at Caldwell, in the county of Essex, State of New Jersey, and ELMER G. CR'oAKMAN,

a citizen of; the United States, residing at Buffalo, county of Erie, State of New York,

have invented certain newand useful Improvements in the Production of Diarylguanidines; and we do herebydeclare the following to be a full, 'clear,.and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to improvementsin etc.

It has heretofore been proposed to make diphenylguanidine 'by the action of lead oxide upon a boiling alcoholic ammoniacal solution of thiocarbanilide, but the yields produced have been poor and the'di'phenylguanidine contaminated with large quantities of resinous or tarlike impurities difii- ,cult to remove.

The present invention is based upon the 1discovery that diarylgu'anidines, such as The invention Will be mail r-illustratedby the following specific example, but it will .be understood .that the invention is not limited thereto.

.In' a jacketed kettle equipped with an agitator, 884 pounds of thiocarbanilide. are dissolved in452 gallons of denatured alcohol v(90%), and 344 niounds of aqueous ammonia of 28.5%strengt (equivalent to 99 pounds of 100% is then added and'the tempound acts as a desulphurizing agent; The

temperature. of the reaction mixture gradually rises. to -45 degrees C. and is prevented from going above this point. litharge' has all been added, the temperature of the charge is maintained at 45 degrees C. -with agitation'for about onehour, or until the reaction is complete.

lVhen the reaction is complete, the mix-- ture is .filtered while maintaining a tem-- Vhen the perature of 45- degrees (1, and theresidue iswashed, first with'alcohol at 45 degrees 6., and then with water. The alcoholic filtrate, which should be clear, is then acidified by the addition of hydrochloric acid 0f 20 degrees Baum until it shows an acid reaction toward brilliant yellow test paper. The acidified and well-stirred solution is then diluted withwater until the amount added is twice the volume of the alcohol present before acidification; solution is stirredfor about one and one-half to two hours and then filtered.-- The solution of diphenylgua-nidine is thus separated The dilute from acid insoluble impurities. I The filtrate is then neutralized with caustic soda, with resulting precipitation of the diphenylguanidine, wliich is immediately filtered oii, thoroughly washed (with water, freed; from excess water in a centrifugal inachine, dried in a current of air at- 60 to 80 C. and ground to a fine pow der. The diphenylgu'anidine is thus obtained substantially free from resinous and tarlike impurities.

In the above example the amount of ammonia is about 50% in excess, and this amount has been found very satisfactory. A larger quantity of aqueous ammonia would dilute the alcohol and thereby de: crease its solvent properties. The amount of alcohol usedin the process, taken in conat the end of the reaction should be of about 80% strength or higher where the reaction is carried out at 45 degrees C. By main taining the solution at that temperature during'filtration from the lead sulphide,

the diphenylguanidine is-kept in solution.

If the solution is allowed to cool, the diphenylguanidine is liable to crystallize out to a greater or less extent.

The temperature used in the process can be somewhat varied, but we have found that,

temperatures considerably below the boiling point of the solution are important in preventing the formation of object onable by-products and in giving a high yield of the diphenylguanidine' For example, at a temperature of 60 degrees (3., a yield of about 77% diphenylguanidine was obtained; at -52 degrees (1., a yield of about 84%, and at 45 degrees (3., a yield of about 88% or more.

The process can be carried out at still lower temperatures, and we have found that even at atmospheric temperatures the reaction readily takes place, but increased amounts of alcohol are necessary at lower temperatures and the resulting solution is accordingly more dilute. For example, wehave found that by first dissolving thiocarbanilide'in alcohol by heating, then allowing the solution to cool and adding ammonium hydroxide and'lead oxide, and by agitating the mixture, the reaction will take place at room temperature, although a longer period of time is required and a somewhat increased amount of lead oxide and ammonia, as well 10 as alcohol, are desirable. The resulting alcoholic solution after filtration from the lead sulphide can be concentrated and the dipheny guanidine separated by acidification, filtration and subsequent precipitation by making the solution alkaline with sodium hydroxide solution, filtering the diphenylguanidine, washing and drying.

The carrying out of the process of the .present invention at low temperatures has the further advantage of greatly reducing the loss of ammonia by volatilization, so

that excessive losses are avoided.-

For best results we have found it important to use lead oxide which is finely divided in character, .for example, lead oxide which will pass through a QOO-mesh screen. The amount of lead oxide mentioned in the above example is about 12% in excess of that required by theory. Larger amounts can be used, particularly if the reaction is carried out at room temperature.

The alcohol used in the process can be recovered by distillation and rectification and used over again in the process.

Other diarylguanidines besides diphenylguanidine can be produced in a similar way. For example, di-o-tolylguanidine, di-ptolylguanidine, etc. Vhere the dairylthiourea is a mixed product, that is, containing two different aryl groups, the diarylguanidine will similarly be a mixed product, thatis, a product containing dilferent aryl groups. I

A mixed ditolyl guanidine can be producedfor example by using as the starting material in making the ditolyl thiourea, the mixture of toluidines produced by reduction of mixed nitroto luenes. For example, the so-called low para cuts may be used which are obtained in conjunction with the manufacture of para-nitrotoluene and which are composed of a mixture consisting-chiefly of ortho-nitrotoluene (about to 95 and para-nitrotoluene (about 3 to .1592),

together with small amounts of metanitrotoluene and possibly other nitro bod-- ies. Upon reducing this mixture, there is produced a sponding toluidines which can 'be used in making the di-tolylureas and in making the ditolyl substituted guanidines in the manner above described.

1. The methodo f producing diarylguanidines, which comprises subjecting an alcoholic, ammoniacal solution of a diarylthiourea to the action of lead oxide at a temperature below about 60 degrees C. Y

r 2. The method of producing diarylguanidines, which comprises subjecting an alcoholic, ammoniacal solution of a diarylthiourea to the actionof lead oxide at a temperature below about 45 degrees C.

3. The method of producing diarylguanidines, which comprises subjecting an alcoholic, ammoniacal solution of a diarylthiourea to the action of lead oxide at a temperature of about 40 to-45 degrees C.

4. The method of producing diphenylguanidine, which comprises subjecting an alcoholic, ammoniacal solution'of thiocarbanilide to the action of lead oxide at a temperature below about 60 degrees C.

5. The method of producing 'diphenylguanidine, which comprises subjecting an alcoholic, ammoniacal solution of thiocarbanilide to the action of lead oxide at a temperature below about 45 degrees C.

6. The method of producing diphenylguanidine, which comprises subjecting an alcoholic, ammoniacal solution of thiocarbanilide to the action of lead oxide at a .dines, which comprises subjecting an alcoinixture of the corre iao " holio, ammoniacal solution of a diarylbanilide to the action of a. leadcompound thiourea. to the action of a' lead compound opting as ,a desulphurizing agent at a temacting as a desulphurizing agent at a tem perature below about 60 degrees: C. 1

perature below about 60 degreos'G. In testimony'whereof we. :iflix our sig- 5 9. The method of producin diphenylnatures guanidine, which comprises su jectmg an JOHN YOUNG v I alcoholic, Emmoniaoal solution of thiocar- I ELMER G CROAKMAN. v 

